Sheet-metal strips are rolled at high temperatures from billets or blooms to a thickness generally ranging between 1.2 and 10 mm. After leaving the last hot-rolling stage, the strip passes over supporting rollers to a coiling station where it is wound on a mandrel. In order to insure even winding, especially when the trailing end of the strip has left the mill, it is customary to position a strip brake immediately upstream of the coiling station whereby the strip is held under tension, e.g. with the aid of a reverse-rotating roller pair. On passing from the rolling mill to the coiling station, the strip may be subjected to forced cooling by means of water sprays.
When arriving at the coiling station, such a strip may have various imperfections including bends at its center, waviness along its lateral edges and thickness irregularities along its cross-section, e.g. because of nonuniform operation of spray heads distributed above the path of the strip. A minor but annoying defect is also the frequently encountered curving of the transverse strip edges at the leading and trailing ends.